Memory device, controller controlling the same, memory system including the same, and operating method thereof

ABSTRACT

A method of operating a memory device includes receiving a training request for a data channel, detecting at least one mode parameter according to the training request, transmitting the detected mode parameter to an external device, setting at least one of an NRZ mode and a PAM4 mode to a transmission signaling mode based on mode register set setting information from the external device, and performing communications with the external device according to the set transmission signaling mode.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims benefit of priority to Korean Patent ApplicationNo. 10-2020-0105217 filed on Aug. 21, 2020 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND

The present disclosure relates to a memory device, a controllercontrolling the same, a memory system including the same, and a methodof operating the same.

In general, the demand for higher-capacity data transmission at higherspeed is growing with extensive deployment of mobile devices and a rapidincrease in Internet traffic. However, it may be difficult for a signalmodulation scheme based on non-return-to-zero (NRZ) type encoding tosatisfy such growing demand for higher-capacity data transmission athigher speed. In recent years, a pulse amplitude modulation (forexample, pulse amplitude modulation 4-level (PAM4)) signaling scheme hasbeen actively developed as an alternative to a signal scheme forhigher-capacity data transmission at higher speed.

SUMMARY

Example embodiments provide a memory device selecting a transmissionsignaling mode, a controller controlling the same, a memory systemincluding the same, and a method of operating the same.

According to example embodiments, a memory device includes memory deviceprocessing circuitry configured to transmit read data to a data channelaccording to a transmission signaling mode, receive write data from thedata channel according to the transmission signaling mode, store thetransmission signaling mode, and perform a training operation on thedata channel in response to a training request received from an externaldevice, to detect at least one mode parameter in the training operation,to select one of a first transmission signaling mode and a secondtransmission signaling mode as the transmission signaling mode using thedetected mode parameter, and to output mode flag information, associatedwith the detected mode parameter, to the external device.

According to example embodiments, a method of operating a memory deviceincludes receiving a training request for a data channel, detecting atleast one mode parameter according to the training request, transmittingthe detected mode parameter to an external device, setting at least oneof a non-return-to-zero (NRZ) mode and a pulse amplitude modulation4-level (PAM4) mode to a transmission signaling mode based on moderegister set setting information from the external device, andperforming communications with the external device according to the settransmission signaling mode.

According to example embodiments, a memory system includes a memorydevice, configured to receive or transmit data through a data channel,according to a transmission signaling mode selected from a firsttransmission signaling mode and a second transmission signaling mode,and a controller configured to control the memory device and to selectthe transmission signaling mode using at least one mode parameter. Thememory device includes memory device processing circuitry configured tostore the transmission signaling mode, and to receive a training requestfrom the controller, to detect at least one mode parameter, associatedwith the data channel, in response to the training request, and totransmit flag information, associated with the detected at least modeparameter, to the controller.

According to example embodiments, a controller controlling a memorydevice includes a controller processing circuitry configured to generatea clock and to output the clock to the memory device, generate a commandaddress signal to operate the memory device, transmit the commandaddress signal in response to the clock, and transmit data to andreceive data from the memory device through a data channel according toa transmission signaling mode selected from a first transmissionsignaling mode and a second transmission signaling mode. Flaginformation, associated with at least one mode parameter, is receivedfrom the memory device during a training period of the memory device,and one of the first transmission signaling mode and the secondtransmission signaling mode is determined to be the transmissionsignaling mode using the flag information.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will be more clearly understood from the following detaileddescription, taken in conjunction with the accompanying drawings.

FIG. 1 is a view illustrating a memory system according to exampleembodiments.

FIGS. 2A and 2B are views illustrating transmission signaling accordingto example embodiments.

FIG. 3 is a view illustrating a mode detection circuit according toexample embodiments.

FIG. 4 is a view illustrating a termination voltage detector accordingto example embodiments.

FIG. 5 is a view illustrating a current detector according to exampleembodiments.

FIG. 6 is a view illustrating a current detector according to exampleembodiments.

FIG. 7 is a view illustrating a channel loss detector according toexample embodiments.

FIG. 8 is a view illustrating a dual-mode transceiver according toexample embodiments.

FIG. 9 is a flowchart illustrating a mode selection method of a memorydevice according to example embodiments.

FIG. 10 a flowchart illustrating a mode selection method of a memorydevice according to example embodiments.

FIG. 11 is a view illustrating a memory system according to exampleembodiments.

FIG. 12A is a ladder diagram illustrating a training operation of amemory system according to example embodiments.

FIG. 12B is a ladder diagram illustrating a training operation of amemory system according to example embodiments.

FIG. 13 is a view illustrating a memory system performing at least onecommand/address calibration according to example embodiments.

FIG. 14 is a view illustrating a memory system according to exampleembodiments.

FIG. 15 is a view illustrating a computing system according to exampleembodiments.

FIG. 16 is a view illustrating a computing system according to exampleembodiments.

FIG. 17 is a view illustrating a data center to which a memory deviceaccording to example embodiments is applied.

DETAILED DESCRIPTION

Hereinafter, example embodiments will be described with reference to theaccompanying drawings.

In a memory system according to example embodiments, a transmissionsignaling mode may be selected based on channel environment informationin a memory device and improved or optimal data transmission may beperformed in the selected transmission signaling mode.

FIG. 1 is a view illustrating a memory system 10 according to exampleembodiments. Referring to FIG. 1, the memory system 10 may include amemory device 100 and/or a controller 200. The memory system 10 may beimplemented as a multi-chip package (MCP) or a system-on-chip (SoC).

The memory device 100 may be configured to store data received from thecontroller 200 or to output read data to the controller 200. The memorydevice 100 may be used as an operation memory, a working memory, or abuffer memory in a computing system. In example embodiments, the memorydevice 100 may be implemented as a single in-line memory module (SIMM),a dual in-line memory module (DIMM), a small-outline DIMM (SODIMM), anunbuffered DIMM (UDIMM), a fully-buffered DIM (FBDIMM), a rank-bufferedDIMM (RBDIMM), a mini-DIMM, a micro-DIMM, a registered DIMM (RDIMM), ora load-reduced DIMM (LRDIMM).

In example embodiments, the memory device 100 may be implemented as avolatile memory. For example, the volatile memory may include at leastone of is dram a dynamic random access memory (DRAM), a synchronous DRAM(SDRAM), a double data rate SDRAM (DDR SDRAM), a low power double datarate SDRAM (LPDDR SDRAM), a graphics double data rate SDRAM (GDDRSDRAM), a Rambus DRAM (RDRAM), and a static RAM (SRAM). In exampleembodiments, the memory device 100 may be implemented as a nonvolatilememory. For example, the nonvolatile memory may include one of a NANDflash memory, a phase-change RAM (PRAM), a magneto-resistive RAM (MRAM),a resistive RAM (ReRAM), a ferroelectric RAM (FRAM), and a NOR flashmemory.

Although not illustrated in the drawing, the memory device 100 mayinclude a serial presence detect (SPD) chip. The SPD chip may beconfigured to store information on characteristics of the memory device100. In example embodiments, the SPD chip may store memory deviceinformation such as a module type, an operating environment, a linearrangement, a module configuration, and storage capacity of the memorydevice 100. In example embodiments, the SPD chip may include aprogrammable read-only memory, for example, an electrically erasableprogrammable read-only memory (EEPROM).

In addition, the memory device 100 may include a mode detection circuit101, a mode register 102, and/or a dual-mode transceiver (XCVR) 103.

The mode detection circuit 101 may be configured to detect an improvedor optimal transmission signaling mode, based on environment informationof a data channel. The transmission signaling mode may include differentmultilevel signaling modes. For example, the transmission signaling modemay include non-return-to-zero (NRZ), pulse amplitude modulation 4-level(PAM4), and the like. For example, the mode detection circuit 101 mayselect an NRZ mode or a PAM4 mode according to channel loss, currentconsumption, or a termination voltage.

The mode register 102 may be configured to store the transmissionsignaling mode selected by the mode detection circuit 101.

The transceiver (XCVR) 103 may be configured to transmit and receivedata through a data channel (DQ channel), according to the transmissionsignaling mode stored in the mode register 102. In example embodiments,the transceiver 103 may be implemented as a dual-mode transceiver.Hereinafter, for ease of description, the transceiver 103 will bereferred to as a dual-mode transceiver.

The dual-mode transceiver 103 may include a transmitter TX and areceiver RX. The transmitter TX of the memory device 100 may beconfigured to transmit read data DRD to the controller 200 through thedata channel, according to a transmission signaling mode PAM4/NRZ. Thereceiver RX of the memory device 100 may be configured to receive writedata DWR from the controller 200 through the data channel, according tothe transmission signaling mode PAM4/NRZ.

The controller 200 may be configured to control the memory device 100.The controller 200 may indicate the transmission signaling mode storedin the memory device 100. The controller 200 may transmit data to andreceive data from the memory device 100 through the data channel,according to the transmission signaling mode.

The controller 200 may include a transceiver 203. The transceiver 203may include a transmitter TX and a receiver RX. The transmitter TX ofthe controller 200 may be configured to transmit write data DWR to thememory device 100 through the data channel, according to thetransmission signaling mode PAM4/NRZ. The receiver RX of the controller200 may be configured to receive the read data DRD from the memorydevice 100 through the data channel, according to the transmissionsignaling mode PAM4/NRZ.

In example embodiments, the controller 200 may be configured as anadditional chip or may be integrated with the memory device 100. Forexample, the controller 200 may be implemented on a mainboard. Inaddition, the controller 200 may be implemented as an integrated memorycontroller (IMC) included in a microprocessor. In addition, thecontroller 200 may be disposed in an input/output hub. The input/outputhub, including the controller 200, may be referred to as a memorycontroller hub (MCH).

In general, data transmission using a PAM4 signal may be advantageous toreduce a channel loss effect as a bandwidth of an interface of a memorydevice is increased.

The memory system 10 according to example embodiments may have aninterface including a transceiver XCVR, capable of providing an NRZ/PAM4dual-mode operation, to perform an improved or optimal transmissionoperation according to a channel environment.

In addition, the memory system 10 according to example embodiments mayinclude the memory device 100, varying an improved or optimaltransmission signaling mode NRZ/PAM4 according to a channel environment,to automatically select a mode.

FIGS. 2A and 2B are views illustrating transmission signaling accordingto example embodiments. Referring to FIG. 2A, two bits of data ‘00’,‘01’, ‘10’, and ‘11’ corresponding to four voltage levels VR1 to VR4 maybe transmitted based on PAM4 transmission signaling. Referring to FIG.2B, one bit of data ‘1’ and ‘0’ corresponding to two voltage levels VLand VH may be transmitted based on NRZ transmission signaling.

It will be understood that the data corresponding to the voltage levels,illustrated in FIGS. 2A and 2B, are only examples.

FIG. 3 is a view illustrating a mode detection circuit 101 according toexample embodiments. Referring to FIG. 3, the mode detection circuit 101may include a termination voltage detector 101-1, a current detector101-2, and/or a channel loss detector 101-3.

The termination voltage detector 101-1 may be configured to detect atermination voltage corresponding to a channel. In some exampleembodiments, the detected termination voltage may be used to select atransmission signaling mode. For example, when the termination voltageis higher than a reference voltage, a PAM4 mode may be selected. Whenthe termination voltage is not higher than the reference voltage, an NRZmode may be selected.

The current detector 101-2 may be configured to detect current consumedby the memory device 100. In some example embodiments, the detectedconsumed current may be used to select a transmission signaling mode.For example, when the consumed current is higher than reference current,the PAM4 mode may be selected. When the consumed current is not higherthan the reference current, the NRZ mode can be selected. As describedabove, it will be understood that the selection of the PAM4 mode and theNRZ mode according to the consumed current is only an example. Forexample, when the consumed current is higher than the reference current,the NRZ mode may be selected. When the consumed current is not higherthan the reference current, the PAM4 mode may be selected.

The channel loss detector 101-3 may be configured to detect loss of adata channel. In some example embodiments, the detected channel loss maybe used to select a transmission signaling mode. For example, when thechannel loss is greater than the reference value, the PAM4 mode may beselected. When the channel loss is not greater than the reference value,the NRZ mode may be selected.

The mode detection circuit 101 according to example embodiments maydetect at least one of the termination voltages, the consumed current,and the channel loss to vary a transmission signaling mode correspondingto the data channel.

It will be understood that the mode detection circuit 101, illustratedin FIG. 3, is only an example. The mode detection circuit according tothe present disclosure may be implemented as at least one of thetermination voltage detector 101-1, the current detector 101-2, and thechannel loss detector 101-3.

FIG. 4 is a view illustrating a termination voltage detector 101-1according to example embodiments. Referring to FIG. 4, the terminationvoltage detector 101-1 may include a comparator CMP. The comparator CMPmay compare a termination voltage Vterm, corresponding to a datachannel, with a reference voltage Vref and may output mode informationMD_term to the mode register 102.

It will be understood that the termination voltage detector 101-1,illustrated in FIG. 4, is only an example.

FIG. 5 is a view illustrating a current detector 101-2 according toexample embodiments. Referring to FIG. 5, the current detector 101-2 mayinclude an amplifier OPAMP. The amplifier OPAMP may compare current,corresponding to power Vreg, with load current I_(LOAD) and may outputmode information MD_crr to the mode register 102.

It will be understood that the current detector 101-2, illustrated inFIG. 5, is only an example of the present disclosure.

The current detector 101-2, illustrated in FIG. 5, may be implementedinside the memory device 100. However, the present disclosure is notnecessarily limited thereto. A current detector according to the presentdisclosure may be disposed outside or external to a memory device.

FIG. 6 is a view illustrating a current detector CD according to exampleembodiments. Referring to FIG. 6, the current detector CD may bedisposed inside a power management circuit PMIC. The current detector CDmay sense the current I_(LOAD) consumed by the memory device 100 and maytransmit mode information MD_crr, corresponding to a detection result,to the memory device 100.

FIG. 7 is a view illustrating a channel loss detector 101-3 according toexample embodiments. Referring to FIG. 7, the channel loss detector101-3 may include comparators configured to compare comparison voltagesV_(REF,RX) and V_(REF,TX) on a channel front end or a channel back endwith each other, a multiplexer configured select one output, amongoutputs of the comparators, in response to a selected signal SEL, and adivider configured to divide an output of the multiplexer. Frequencyinformation, output from the divider, may include mode informationMD_loss and may be input to the mode register 102.

It will be understood that the channel loss detector 101-3, illustratedin FIG. 7, is only an example of the present disclosure. Voltages on thechannel front end and the channel back end may be simply compared witheach other to detect mode information MD_loss corresponding to channelloss.

FIG. 8 is a view illustrating a dual-mode transceiver 103 according toexample embodiments. Referring to FIG. 8, a transmitter TX of thedual-mode transceiver 103 may include a serializer MUX/SER, a firstdriver 103-1, and/or a second driver 103-2.

The serializer MUX/SER may convert and output parallel data DATA1 toDATAn into serial data, according to a transmission signaling mode.

The first driver 103-1 may be activated in response to a firsttransmission signaling mode signal NRZ. The first driver 103-1 maytransmit and receive a data signal, according to an NRZ signalingscheme.

The second driver 103-2 may be activated in response to a secondtransmission signaling mode signal PAM4. The second driver 103-2 maytransmit and receive data signals, according to a PAM4 signaling scheme.In example embodiments, the second driver 103-2 may include a low swingdriver LSD, configure to generate signals having low swing levels (VR2and VR3 of FIG. 2A), and a high swing driver HSD configured to generatesignals having high swing levels (VR1 and VR4 of FIG. 2A). The detaileddescription of the second driver 103-2 is disclosed in U.S. Pat. No.10,312,896, the disclosure of which is incorporated herein by reference.

As illustrated in FIG. 8, each of the first driver 103-1 and the seconddriver 103-2 may include at least one pull-up driver between a powersupply terminal VDD and an output terminal OUT and at least onepull-down driver between the output terminal OUT and a ground terminal.

FIG. 9 is a flowchart illustrating a mode selection method of a memorydevice 100 according to example embodiments. Hereinafter, the modeselection method of the memory device 100 will be described withreference to FIGS. 1 to 9.

The memory device 100 may basically communicate with the controller 200in the NRZ mode (S110). A determination may be made as to whether a halfvalue BW/2 of a bandwidth corresponding to a data channel is greaterthan a reference bandwidth dB_ref (S120). When the half value BW/2 ofthe bandwidth is not greater than the reference bandwidth dB_ref, adetermination may be made as to whether consumed current I is higherthan reference current I_ref (S130). When the consumed current I is notgreater than the reference current I_ref, a determination may be made asto whether a termination voltage V is higher than a reference voltageV_ref (S140). When the termination voltage V is not higher than thereference voltage V_ref, the NRZ mode may be maintained (S150).

When the half value BW/2 of the bandwidth is greater than the referencebandwidth dB_ref, the consumed current I is higher than the referencecurrent I_ref, or the termination voltage V is greater than thereference voltage V_ref, the PAM4 mode may be selected (S160).

It will be understood that a comparison criterion for the bandwidth,illustrated in FIG. 9 is not limited to the half value of BW/2 of thebandwidth.

Also, it will be understood that the operation order, illustrated inFIG. 9, is only an example of the present disclosure.

In the mode selection method described in FIG. 9, the NRZ mode is set toa default mode, but the present disclosure is not limited thereto. Inthe mode selection method according to the present disclosure, a PAM4mode may be set to a default mode.

FIG. 10 a flowchart illustrating a mode selection method of a memorydevice 100 according to example embodiments. Hereinafter, the modeselection method of the memory device 100 will be described withreference to FIGS. 1 to 10.

The memory device 100 may basically communicate with the controller 200in the PAM4 mode (S210). A determination may be made as to whether ahalf value BW/2 of a bandwidth corresponding to a data channel isgreater than a reference bandwidth dB_ref (S220). When the half valueBW/2 of the bandwidth is greater than the reference bandwidth dB_ref, adetermination may be made as to whether consumed current I is higherthan reference current I_ref (S230). When the consumed current I ishigher than the reference current I_ref, a determination may be made asto whether a termination voltage V is higher than a reference voltageV_ref (S240). When the termination voltage V is higher than thereference voltage V_ref, the PAM4 mode may be maintained (S250).

When the half value BW/2 of the bandwidth is not greater than thereference bandwidth dB_ref, the consumed current I is not higher thanthe reference current I_ref, or the termination voltage V is not greaterthan the reference voltage V_ref, the NRZ mode may be selected (S260).

In general, a training operation may be performed on a memory device ina startup or specific situation. The training may allow a controller toenhance reliability of data or signal exchange with the memory device.For example, training data may be written to or read from the memorydevice under various conditions to determine an improved or optimalclock timing or reference level. A mode selection operation of thememory device 100 according to the present disclosure may be performedduring a training operation period.

FIG. 11 is a view illustrating a memory system 20 according to exampleembodiments. Referring to FIG. 11, as compared with the memory system 10illustrated in FIG. 1, the memory system 20 may include a controller 200a including a training logic 201. The training logic 201 may perform atraining operation on a data channel of a memory device 100 tocommunicate with the memory device 100, according to a predetermined oralternatively, desired scheme. According to such a training operation,the memory device 100 may detect and select a transmission signalingmode most appropriate to the data channel.

The transmission signaling mode may be selected by setting a moderegister set (MRS) using a detected mode parameter according to exampleembodiments.

FIG. 12A is a ladder diagram illustrating a training operation of amemory system according to example embodiments. Hereinafter, a trainingoperation in a memory device MEM and a controller CNTL will be describedwith reference to FIGS. 1 to 11.

Before performing communication, the controller CNTL may transmit atraining request (or a training command) to the memory device MEM (S10).The memory device MEM may perform a training operation, corresponding toa data channel, in response to the training request. In particular, thememory device MEM may detect at least one mode parameter to select atransmission signaling mode improved or optimal for the data channel(S11). The at least one mode parameter may include consumed current, atermination voltage, and channel loss associated with the data channel.The memory device MEM may transmit flag information, associated with thedetected mode parameter, to the controller CNTL (S12). The controllerCNTL may select a transmission signaling mode, based on the flaginformation (S13). The controller CNTL may transmit MRS information forsetting the transmission signaling mode to the memory device MEM (S14).The memory device 100 may perform MRS setting associated with thetransmission signaling mode PAM4/NRZ, based on the MRS information(S15).

In the memory system according to the present disclosure, transmissionsignaling mode setting is not necessarily limited to the MRS setting.The memory system according to the present disclosure may select atransmission signaling mode using a mode parameter detected by a memorydevice.

FIG. 12B is a ladder diagram illustrating a training operation of amemory system according to example embodiments. Hereinafter, a trainingoperation in a memory device MEM and a controller CNTL will be describedwith reference to FIGS. 1 to 11.

Before performing communication, the controller CNTL may transmit atraining request (or a training command) to the memory device MEM (S20).The memory device MEM may perform a training operation, corresponding toa data channel, in response to the training request and may detect atleast one mode parameter as a result of the training operation (S11).The memory device MEM may select a transmission signaling mode PAM4/NRZusing a detected mode parameter (S22). The memory device MEM maytransmit mode flag information, corresponding to the selectedtransmission signaling mode PAM4/NRZ, to the controller CNTL (S23). Thecontroller CNTL may select the transmission signaling mode PAM4/NRZ,based on the mode flag information (S24).

It will be understood that the methods of selecting a transmissionsignaling mode using a detected mode parameter, described in FIGS. 12Aand 12B, are only examples of the present disclosure.

FIG. 13 is a view illustrating a memory system performing at least onecommand/address calibration according to example embodiments.

Referring to FIG. 13, a memory system 1000 may include a controller 1800and/or a memory device 1900. The controller 1800 may include a clockgenerator 1801, a command/address (CA) generator 1802, a command/addressreference generator 1803, a register 1804, a comparator 1806, aphase/timing controller 1808, and/or data input/output units 1810 and1812. The controller 1800 may provide a clock signal CK, generated bythe clock generator 1801, to the memory device 1900 through a clocksignal line.

In example embodiments, the memory system 1000 may have an additionalcommand/address reference signal (CA_Ref) line provided in an interface.The command/address reference signal (CA_Ref) line may serve to transmitand receive a reference signal CA_Ref of a command/address, a referencevalue of a command/address, in a calibration mode.

A calibration result value using such a reference value of thecommand/address may be provided to the phase/timing controller 1808 toadjust phase/timing of the command/address signal CA. Since there is theadditional command/address reference signal (CA_Ref) line, a calibrationoperation may be performed to adjust phase/timing of the command/addresssignal CA while performing an operation to transmit the command/addresssignal CA.

The CA generator 1802 may generate a phase or timing-adjustedcommand/address signal CA in response to a control signal CTR of thephase/timing controller 1808, and may transmit phase or timing-adjustedcommand/address signal CA to a memory device 1900.

The command/address reference generator 1803 may have the sameconfiguration as the command/address generator 1802 and may generate afirst command/address reference signal CA_Ref, identical to thecommand/address signal CA generated by the command/address generator1802.

A first command/address reference signal CA_Ref1 may be provided to theregister 1804. Also, the first command/address reference signal CA_Ref1may be transmitted to a CA reference bus 16 through a data output unit1812 and may be provided to the memory device 1900 through the CAreference bus 16.

The register 1804 may store the first command/address reference signalCA_Ref1. The comparator 1806 may compare the first command/addressreference signal CA_Ref1, stored in the register 1804, with a thirdcommand/address reference signal CA_Ref3 output from the data input unit1810. The comparator 1804 may compare data of the first command/addressreference signal CA_Ref1 with data of the third command/addressreference signal CA_Ref3 to generate a pass or fail signal P/F.

The phase/timing controller 1808 may generates a control signal CTRindicating a phase shift of the command/address signal CA according tothe pass or fail signal P/F of the comparator 1806. The control signalCTR may adjust a phase or timing of the command/address signal CA togenerate a phase-adjusted command/address signal CA.

The data input unit 1810 may receive a second command/address referencesignal CA_Ref2, transmitted through a CA reference bus, from the memorydevice 1900 and may transmit the second command/address reference signalCA_Ref2 to the comparator 1806 as the third command/address referencesignal CA_Ref3.

The data output unit 1812 may receive the first command/addressreference signal CA_Ref1, generated by the command/address referencegenerator 1803, and transmit the first command/address reference signalCA_Ref1 to a CA reference bus 12.

The memory device 1900 may include a clock buffer 1902, acommand/address (CA) receiver 1904, a command/address reference receiver1906, and/or data input/output units 1908 and 910. The clock buffer 1902may receive a clock signal CK, transmitted through a clock signal line,to generate an internal clock signal ICK. The CA receiver 1904 mayreceive a chip select signal/CS, a clock enable signal CKE, and acommand/address signal CA, transmitted through a CA bus, in response tothe internal clock signal ICK.

The clock enable signal CKE may be used as a pseudo command acting as aread command of the command/address signal CA transmitted through the CAbus. The CA receiver 1904 may receive the command/address signal CA whenthe clock enable signal CKE is activated.

The data input unit 1908 may receive the first command/address referencesignal CA_Ref1, transmitted through the CA reference bus, from thecontroller 1800 and may transmit the first command/address referencesignal CA_Ref1 to the command/address reference receiver 1906. Thecommand/address reference receiver 1906 may have the same configurationas the CA receiver 1904. The command/address reference receiver 1906 mayreceive the chip select signal/CS, the clock enable signal CKE, and thefirst command/address reference signal CA_Ref1, transmitted through theCA reference bus, in response to an internal clock signal ICK togenerate a second command/address reference signal CA_Ref2.

The second command/address reference signal CA_Ref2 may be the same as asignal output from the CA receiver 1904 by receiving the chip selectsignal/CS, the clock enable signal CKE, and the command/address signalCA, transmitted through the CA bus, in response to the internal clocksignal ICK. The second command/address reference signal CA_Ref2 may betransmitted to the CA reference bus through the data output unit 1910.

Hereinafter, CA calibration performed in the memory system 1000 will bedescribed. The CA generator 1802 of the controller 1800 may adjust aphase or timing of the command/address signal CA in response to acontrol signal CTR of the phase/timing controller 1808 to transmit thecommand/address signal CA to a CA bus. The command/address referencegenerator 1803 may generate a first command/address reference signalCA_Ref1, identical to the command/address signal CA, and may transmitthe first command/address reference signal CA_Ref1 to a CA referencebus.

The CA reference receiver 1906 of the memory device 1900 may receive thefirst command/address reference signal CA_Ref1 according to the internalclock signal ICK and the clock enable signal CKE to generate a secondcommand/address reference signal CA_Ref2. The second command/addressreference signal CA_Ref2 of the memory device 1900 may be transmitted tothe CA reference bus.

The controller 1800 may transmit the first command/address referencesignal CA_Ref1, transmitted through the CA reference bus, to thecomparator 1806 as the second command/address reference signal CA_Ref2.The comparator 1806 may compare data of the first command/addressreference signal CA_Ref1 with data of the second command/addressreference signal CA_Ref2 to generate a pass or fail signal P/E. Thephase/timing controller 1808 may generate a control signal CTR,indicating a phase shift of the command/address signal CA, according tothe pass or fail signal P/F of the comparator 1806. The CA generator1802 may generate a phase-adjusted command/address signal CA accordingto the control signal CTR.

With the repetition of such a CA calibration operation, the phase/timingcontroller 1808 of the controller 1800 may determine the middle oflocations passed (P) to be the middle of a command/address signal (CA)window, and may generate a command/address signal CA to bring the middleof the command/address signal (CA) window into an edge of the clocksignal CK and provide the command/address signal CA to the memory device1900. Accordingly, the memory device 1900 may receive a command/addresssignal CA in which the middle of an effective window is disposed onrising/falling edges of a pair of clock signals (a clock signal pair) CKand CKB on rising/falling edges of the clock signal CK.

The memory system 1000 according to example embodiments may include thedual-mode transceiver 1820 and 1920, described with reference to FIGS. 1to 12B, respectively provided in the controller 1800 and the memorydevice 1900.

In example embodiments, each of the dual-mode transceivers 1820 and 1920may select one of the NRZ and PAM4 modes through a plurality of datachannels DQ in real time, and may transmit data to the selected mode.

A memory system according to example embodiments may be disposed on asingle substrate.

FIG. 14 is a view illustrating a memory system 2000 according to exampleembodiments. Referring to FIG. 14, the memory system 200 may include acontrol chip 2100 and/or a memory chip 2200 mounted on a substrate 2001.In example embodiments, the control chip 2100 and the memory chip 2200may connected to each other through the substrate 2001 provided with aninterposer. Each of the control chip 2100 and the memory chip 2200 mayinclude a dual-mode transceiver DUAL-MODE XCVR described in FIGS. 1 to12B.

A memory device according to example embodiments may be applied to acomputing system.

FIG. 15 is a view illustrating a computing system 300 according toexample embodiments. Referring to FIG. 15, the computing system 2000 mayinclude at least one volatile memory module (DIMM(s)) 3100, at least onenonvolatile memory module (NVDIMM(s)) 3200, and/or at least one centralprocessing unit (CPU(s)) 3300.

The computing system 3000 may be used as one of a plurality of devicessuch as a computer, a portable computer, an ultra-mobile personalcomputer (UMPC), a workstation, a data server, a net-book, a personaldata assistant (PDA), a web tablet, a wireless phone, a mobile phone, asmartphone, an e-book, a portable multimedia player (PMP), a digitalcamera, a digital audio recorder/player, a digital picture/videorecorder/player, a portable game machine, a navigation system, a blackbox, a 3D television, a device capable of transmitting and receivinginformation at a wireless circumstance, a wearable device, one ofvarious electronics devices constituting a home network, one of variouselectronics devices constituting a computer network, one of variouselectronics devices constituting a telematics network, a radio-frequencyidentification (RFID), one of various electronic devices constituting acomputing system, or the like.

The at least one nonvolatile memory module 3200 may include at least onenonvolatile memory. In example embodiments, the at least one nonvolatilememory may include a NAND flash memory, a vertical NAND flash memory(VNAND), a NOR flash memory, a resistive random access memory (RRAM), aphase-change memory (PRAM), a magneto-resistive random access memory(MRAM), a ferroelectric random access memory (FRAM), a spin transfertoque random access memory (STT-RAM), a thyristor random access memory(TRAM), or the like.

In example embodiments, at least one of the memory modules 3100 and 3200may vary the multilevel transmission signaling mode, described in FIGS.1 to 12 according to a channel environment, and may include an interfacecircuit IF performing data communications with the central processingunit 3300 according to the varied transmission signaling mode.

In example embodiments, the memory modules 3100 and 3200 may beconnected to the central processing unit 3300 according to a DDRxinterface (where x is an integer of 1 or more).

The at least one central processing unit 3300 may be implemented tocontrol the volatile memory module 3100 and the nonvolatile memorymodule 3200. In example embodiments, the central processing unit 3300may include a general purpose microprocessor, a multicore processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), or a combination thereof.

A transmission signaling mode variation according to example embodimentsmay be performed in a stacked memory package chip.

FIG. 16 is a view illustrating a computing system according to exampleembodiments. Referring to FIG. 16, a computing system 4000 may include ahost processor 4100 and/or at least one memory package chip 4210controlled by the host processor 4100.

In example embodiments, the host processor 4100 and the memory packagechip 4210 may transmit and receive data through a channel 4001.

The memory package chip 4210 may include stacked memory chips and acontroller chip. As illustrated in FIG. 16, the memory package chip 4210may include a plurality of DRAM chips disposed on a DRAM controllerchip. It will be understood that a configuration of the memory packagechip according to the present disclosure is not limited thereto.

In example embodiments, a transmission signaling mode may vary accordingto an internal channel environment between stacked memory chips and acontroller chip of the memory package chip 4210.

In example embodiments, a transmission signaling mode may vary, in realtime, according to a channel environment between the host processor 4100and the memory package chip 4210.

A data communications method according to the present disclosure may beapplied to a data center.

FIG. 17 is a view illustrating a data center to which a memory deviceaccording to example embodiments is applied. Referring to FIG. 17, adata center 7000 is a facility, collecting various types of data andproviding services, and may also be referred to as a data storagecenter. The data center 7000 may be a system for managing a searchengine and database, and may be a computing system used in a companysuch as a bank or (an organization such as) a government agency. Thedata center 7000 may include application servers 7100 to 7100 n and/orstorage servers 7200 to 7200 m. The number of application servers 7100to 7100 n and the number of storage servers 7200 to 7200 m may bevariously selected according to example embodiments, and the number ofapplication servers 7100 to 7100 n and storage servers 7200 to 7200 mmay be different from each other.

The application server 7100 or the storage server 7200 may include atleast one of the processors 7110 and 7210 and the memories 7120 and7220. To describe the storage server 7200 as an example, the processor7210 may control overall operation of the storage server 7200 and mayaccess the memory 7220 to execute a command and/or data loaded in thememory 7220. The memory 7220 may be a double data rate synchronous DRAM(DDR SDRAM), a high bandwidth memory (HBM), a hybrid memory cube (HMC),a dual in-line memory module (DIMM), an optane DIMM, or a non-volatileDIMM (NVMDIMM). According to example embodiments, the number of theprocessor 7210 included in the storage server 7200 may be variouslyselected.

In example embodiments, the processor 7210 and the memory 7220 mayprovide a processor-memory pair. In example embodiments, the number ofthe processors 7210 and the memories 7220 may be different from eachother. The processor 7210 may include a single-core processor or amultiple core processor. The description of the storage server 7200 maybe similarly applied to the application server 7100. According toexample embodiments, the application server 7100 may not include thestorage device 7150. The storage server 7200 may include at least onestorage device 7250. The storage device 7259 may be configured to vary atransmission signaling mode according to a channel environment, asdescribed with reference to FIGS. 1 to 16.

The application servers 7100 to 7100 n and the storage servers 7200 to7200 m may communicate with each other through a network 7300. Thenetwork 7300 may be implemented using a fiber channel (FC), an Ethernet,or the like. The FC may be a medium used for data transmission atrelatively high speed and may employ an optical switch for providinghigher performance/higher availability. The storage servers 7200 to 7200m may be provided as a file storage, a block storage, or an objectstorage according to an access method of the network 7300.

In example embodiments, the network 7300 may be a storage area network(SAN). For example, the SAN may be an FC-SAN using an FC network andimplemented according to an FC protocol (FCP). As another example, theSAN may be an IP-SAN using a TCP/IP network and implemented according toa SCSI over TCP/IP or Internet SCSI (iSCSI) protocol. In exampleembodiments, the network 7300 may be a general network such as a TCP/IPnetwork. For example, the network 7300 may be implemented according to aprotocol such as an FC over Ethernet (FCoE), a network attached storage(NAS), an NVMe over Fabrics (NVMe-oF), or the like.

Hereinafter, a description will be provided while focusing on theapplication server 7100 and the storage server 7200. The description ofthe application server 7100 may be applied to another application server7100 n, and the description of the storage server 7200 may be applied toanother storage server 7200 m.

The application server 7100 may store data, requested to be stored by auser or a client, in one of the storage servers 7200 to 7200 m throughthe network 7300. In addition, the application server 7100 may obtaindata, requested to be read by the user or the client, from one of thestorage servers 7200 to 7200 m through the network 7300. For example,the application server 7100 may be implemented as a web server, adatabase management system (DBMS), or the like.

The application server 7100 may access the memory 7120 n or the storagedevice 7150 n included in another application server 7100 n through thenetwork 7300, or may access the memories 7200 to 7200 m or the storagedevices or the storage devices 7250 to 7250 m included in the memory7220 to 7220 m through the network 7300. Accordingly, the applicationserver 7100 may perform various operations on data stored in theapplication servers 7100 to 7100 n and/or storage servers 7200 to 7200m. For example, the application server 7100 may execute a command tomove or copy data between the application servers 7100 to 7100 n and/orstorage servers 7200 to 7200 m. In some example embodiments, the datamay be moved from the storage servers 7200 to 7200 m to the storagedevices 7250 to 7250 m to the storage servers 7200 to 7200 m throughmemories 7220 to 7220 m, or may be directly moved to the memories 7120to 7120 n of the application servers 7100 to 7100 n. Data, moved throughthe network 7300, may be data encrypted for security or privacy.

To describe the storage server 7200 as an example, the interface 7254may provide a physical connection between the processor 7210 and acontroller 7251 and a physical connection between an NIC 7240 and thecontroller 7251. For example, the interface 7254 may be implemented by adirect attached storage (DAS) method in which the storage device 7250 isdirectly connected to an exclusive cable. In addition, for example, theinterface 1254 be implemented in various interface manners such asAdvanced Technology Attachment (ATA), Serial ATA (SATA), external SATA(e-SATA), Small Computer Small Interface (SCSI), Serial Attached SCSI(SAS), Peripheral PCI Component Interconnection (PCI express), PCIe (NVexpress), NVMe (NVM express), IEEE 1394, universal serial bus (USB),secure digital (SD) card, multi-media card (MMC), embedded multi-mediacard (eMMC), Universal Flash Storage (UFS), Embedded Universal FlashStorage (eUFS), Compact Flash (CF) card interface, and the like.

The storage server 7200 may further include a switch 7230 and an NIC7240. The switch 7230 may selectively connect the processor 7210 and thestorage device 7250 to each other or selectively connect the NIC 7240and the storage device 7250 to each other under the control of theprocessor 7210.

In example embodiments, the NIC 7240 may include a network interfacecard, a network adapter, and the like. The NIC 7240 may be connected tothe network 7300 by a wired interface, a wireless interface, a Bluetoothinterface, an optical interface, or the like. The NIC 7240 may includean internal memory, a DSP, a host bus interface, and the like, and maybe connected to the processor 7210 and/or the switch 7230 through a hostbus interface. The host bus interface may be implemented as one of theabove-described examples of the interface 7254. In example embodiments,the NIC 7240 may be integrated with at least one of the processor 7210,the switch 7230, and the storage 7250.

In the storage servers 7200 to 7200 m or the application servers 7100 to7100 n, the processor may transmit data to the storage device 7130 to7130 n and 7250 to 7250 m or transmit a command to the memory 7120 to7120 n and 7220 to 7220 m to program or read the data. In some exampleembodiments, the data may be error-corrected data corrected through anerror correction code (ECC) engine. The data is data subjected to databus inversion (DBI) or data masking (DM), and may include cyclicredundancy code (CRC) information. The data may be data encrypted forsecurity or privacy.

The storage device 7150 to 7150 m and 7250 to 7250 m may transmit acontrol signal and a command/address signal to the NAND flash memorydevices 7252 to 7252 m in response to a read command received from theprocessor. Accordingly, when data is read from the NAND flash memorydevice 7252 to 7252 m, a read enable signal RE may be input as a dataoutput control signal to serve to output data to a DQ bus. A data strobeDQS may be generated using the read enable signal RE. The command andthe address signal may be latched in a page buffer according to a risingedge or a falling edge of a write enable signal WE.

The controller 7251 can control overall operation of the storage device7250. In example embodiments, the controller 7251 may include a staticrandom access memory (SRAM). The controller 7251 may write data to theNAND flash 7252 in response to a write command, or may read data fromthe NAND flash 7252 in response to a read command. For example, thewrite command and/or the read command may be provided from the processor7210 in the storage server 7200, the processor 7210 m in another storageserver 7200 m, or the processors 7110 and 7110 n in the applicationservers 7100 and 7100 n. The DRAM 7253 may temporarily store (buffer)data to be written to the NAND flash 7252 or data read from the NANDflash 7252. In addition, the DRAM 7253 may store metadata. The metadatais user data or data generated by the controller 7251 to manage the NANDflash memory 7252. The storage device 7250 may include a secure element(SE) for security or privacy.

As described above, example embodiments provide a memory deviceselecting a transmission signaling mode, a controller controlling thesame, a memory system including the same, and a method of operating thesame. The memory device may select a transmission signaling modeaccording to a channel environment and may transmit and receive dataaccording to the selected transmission signaling mode to automaticallyperform communications under an improved or optimal environment.

In addition, the memory device may detect and select an improved oroptimal transmission signaling mode during a training period to operateadaptively to a channel environment.

One or more of the elements disclosed above may include or beimplemented in processing circuitry such as hardware including logiccircuits; a hardware/software combination such as a processor executingsoftware; or a combination thereof. For example, the processingcircuitry more specifically may include, but is not limited to, acentral processing unit (CPU), an arithmetic logic unit (ALU), a digitalsignal processor, a microcomputer, a field programmable gate array(FPGA), a System-on-Chip (SoC), a programmable logic unit, amicroprocessor, application-specific integrated circuit (ASIC), etc.

While example embodiments have been shown and described above, it willbe apparent to those skilled in the art that modifications andvariations could be made without departing from the scope of the presentinventive concepts as defined by the appended claims.

What is claimed is:
 1. A memory device comprising: memory deviceprocessing circuitry configured to transmit read data to a data channelaccording to a transmission signaling mode; receive write data from thedata channel according to the transmission signaling mode; store thetransmission signaling mode; and perform a training operation on thedata channel in response to a training request received from an externaldevice, to detect at least one mode parameter in the training operation,to select one of a first transmission signaling mode and a secondtransmission signaling mode as the transmission signaling mode using thedetected mode parameter, and to output mode flag information, associatedwith the detected mode parameter, to the external device.
 2. The memorydevice of claim 1, wherein the first transmission signaling mode is anon-return-to-zero (NRZ) mode, and the second transmission signalingmode is a pulse amplitude modulation 4-level (PAM4) mode.
 3. The memorydevice of claim 1, wherein the at least one parameter comprises at leastone of a termination voltage corresponding to the data channel, currentconsumed by the memory device, and channel loss of the data channel. 4.The memory device of claim 3, wherein the memory device processingcircuitry comprises a mode detection circuit which further comprises atermination voltage detector configured to detect the transmissionsignaling mode by comparing the termination voltage with a referencevoltage.
 5. The memory device of claim 3, wherein the mode detectioncircuit comprises a current detector configured to detect thetransmission signaling mode by comparing the current, consumed by thememory device, with reference current.
 6. The memory device of claim 3,wherein the mode detection circuit comprises a channel loss detectorconfigured to detect the transmission signaling mode by comparing avoltage of the data channel with a predetermined voltage.
 7. The memorydevice of claim 1, wherein the memory device processing circuitryfurther comprises a transmitter which further comprises: a serializerconfigured to convert received parallel data into serial data accordingto the transmission signaling mode; a first driver configured to outputthe converted serial data according to the first transmission signalingmode; and a second driver configured to output the converted serial dataaccording to the second transmission signaling mode.
 8. The memorydevice of claim 1, wherein the transmission signaling mode is an NRZmode as a default mode, and the transmission signaling mode is selectedfrom the NRZ mode to the PAM4 mode according to the at least oneparameter.
 9. The memory device of claim 1, wherein the memory deviceprocessing circuitry comprises a mode detection circuit configured totransmit mode selection information, associated with the selectedtransmission signaling mode, to the external device.
 10. The memorydevice of claim 1, wherein the transmission signaling mode is stored inthe memory device processing circuitry a using a mode register setreceived from the external device.
 11. A method of operating a memorydevice, the method comprising: receiving a training request for a datachannel; detecting at least one mode parameter according to the trainingrequest; transmitting the detected mode parameter to an external device;setting at least one of a non-return-to-zero (NRZ) mode and a pulseamplitude modulation 4-level (PAM4) mode to a transmission signalingmode based on mode register set setting information from the externaldevice; and performing communications with the external device accordingto the set transmission signaling mode.
 12. The method of claim 11,wherein the detecting of the at least one mode parameter comprises:determining whether a bandwidth corresponding to the data channel isgreater than a reference value; determining whether current consumed bythe memory device is higher than reference current; or determiningwhether a termination voltage corresponding to the data channel ishigher than a reference voltage.
 13. The method of claim 12, furthercomprising: performing communications in the NRZ mode as a default mode.14. The method of claim 13, wherein the selecting of the transmissionsignaling mode comprises selecting the PAM4 mode when the bandwidth isgreater than the reference value, when the consumed current is higherthan the reference current, or when the termination voltage is higherthan the reference voltage.
 15. The method of claim 12, furthercomprising: performing communications in the PAM4 mode as a defaultmode, wherein the selecting of the transmission signaling mode comprisesselecting the NRZ mode when the bandwidth is not greater than thereference value, when the consumed current is not higher than thereference current, or when the termination voltage is not higher thanthe reference voltage.
 16. A memory system comprising: a memory deviceconfigured to receive or transmit data through a data channel, accordingto a transmission signaling mode selected from a first transmissionsignaling mode and a second transmission signaling mode; and acontroller configured to control the memory device and to select thetransmission signaling mode using at least one mode parameter, whereinthe memory device comprises: memory device processing circuitrycomprises configured to store the transmission signaling mode; andreceive a training request from the controller, to detect at least onemode parameter, associated with the data channel, in response to thetraining request, and to transmit flag information, associated with thedetected at least mode parameter, to the controller.
 17. The memorysystem of claim 16, wherein the controller comprises: controllerprocessing circuitry corresponding to the data channel; and configuredto make a training request for the data channel, and wherein thetransmission signaling mode is detected by the memory device processingcircuitry according to the training request.
 18. The memory system ofclaim 16, wherein the controller is configured to communicate with thememory device according to the transmission signaling mode stored in themode register.
 19. The memory system of claim 16, wherein one bit ofdata, corresponding to each of a first voltage level and a secondvoltage level higher than the first voltage level, is transmittedthrough the data channel according to the first transmission signalingmode.
 20. The memory system of claim 16, wherein two bits of data,corresponding to each of a first voltage level, a second voltage levelhigher than the first voltage level, a third voltage level higher thanthe second voltage level, and a fourth voltage level higher than thethird voltage level, are transmitted through the data channel accordingto the second transmission signaling mode.